The predictors and maintaining factors of non-suicidal self-injury (NSSI) among psychiatric adults remains a critical area of research requiring empirical attention. A growing body of research has elucidated several cross-sectional risk factors for NSSI (e.g., emotional dysregulation, depression; Andover, Morris, Wren, & Bruzzese, 2012). These findings are consistent with theoretical models, including the four function model (Nock & Prinstein, 2004, 2005) and the affect regulation model (see Klonsky, 2007), highlighting the role of negative affect in NSSI. Recent findings indicate that some individuals self-identify a self-injurers and engage in NSSI to preserve identity (Breen, Lewis, & Sutherland, 2013). However, investigation of the role of NSSI identity (e.g., identifying as a cutter) for the onset and maintenance of NSSI remains scarce and the available research contains methodological limitations (e.g., self-report methodology; Nock & Banaji, 2007). The proposed study aims to advance knowledge of the role of NSSI identity in the maintenance and severity of NSSI in a mixed methods study design. The overall goal is congruent with National Institute of Mental Health's Strategic Objective 2.3, to develop tools to better define and identify risk and protective factors for mental illness across the lifespan. Specifically, we will examine the construct of NSSI identity through the collection of original quantitative and qualitative data examining both implicit (i.e., automatic; laboratory-based) and explicit (i.e., self-reported) identification with NSSI. The proposed project will enhance existing knowledge by using a mixed methods design to explore this novel construct in the context of NSSI research. The aims of the project are (1) examine the stability of implicit NSSI identity, compared to attitude toward NSSI, in a one week, test-retest design, (2) explore the impact of implicit NSSI identity on maintenance and severity of NSSI, and (3) explore explicit NSSI identity and its relationship to implicit NSSI identity through qualitative interviews and mixed methods analysis. The proposed research and training plan will provide the PI with training in (1) theoretical and analytical understanding of mixed methods design in the scientific study of NSSI, (2) advanced training in both quantitative and qualitative methodology and analysis, (3) use of a NSSI-specific laboratory-based behavioral assessment measure of NSSI, the Self-Injury Implicit Association Task (SI-IAT; Nock & Banaji, 2007), (4) understanding implicit and explicit processes associated with NSSI, (5) further experience in scientific writing and research dissemination, and (6) the ethical conduct of innovative NSSI research in an acute treatment setting. This research has direct implications for clinical practice. Improved knowledge about the role NSSI identity may play in treatment adherence and development of alternative coping strategies to manage distress will enhance understanding of factors that maintain NSSI, offering critical information fo prevention and intervention efforts, treatment development, and risk assessment and management.